Doppler-guided retrograde catheterization using transducer equipped guide wire

ABSTRACT

A method and apparatus for Doppler-guided, imaged intravascular catherization of a higher mammal includes inserting into a peripheral blood vessel a steerable catheter which has a guide wire provided with a Doppler ultrasound transceiver at its tip, generating from signals produced by the ultrasound transceiver a continuous indication of the direction of blood flow direction relative to the catheter tip, visually displaying the indications on a display monitor, and advancing the catheter towards the heart in accordance with the indication of blood flow direction until the catheter is positioned at a desired location within the circulatory system of the mammal.

RELATED APPLICATIONS

This is a continuation-in-part of co-pending U.S. patent applicationSer. No. 07/669,052, filed Mar. 14, 1991, for DOPPLER-GUIDED AND IMAGEDRETROGRADE CATHETERIZATION, which is a continuation-in-part of U.S.patent application Ser. No. 07/413,953, filed Sep. 28, 1989, for METHODAND DEVICE FOR DOPPLER-GUIDED RETROGRADE CATHETERIZATION, now U.S. Pat.No. 5,038,789.

BACKGROUND OF THE INVENTION

The present invention relates to a procedure for the intravascularcatheterization of higher mammals, and in particular to a method anddevice for imaged retrograde arterial catheterization withoutradiographic guidance. Specifically, the invention pertains to the useof a catheter or guide wire-mounted Doppler ultrasound transceiver toselectively guide the catheter along the arterial tree towards theheart.

Vascular catheterization is practiced medically for a variety ofreasons, and is used in both diagnostic and therapeutic procedures. Inthe case of radioangiography, for example, the catheter is used todeliver a radiopaque dye to a desired point in the circulatory system.The dye is then injected and is passively distributed while beingvisualized via fluoroscopy or radiography, providing an indication ofblood flow and distribution. Alternatively, the catheter may carry adevice for the treatment of intra-vascular defects, such as aninflatable balloon which can be used to enlarge an area of vascularconstriction.

Diagnostic devices can be attached to such catheters so as to allow thetaking of intravascular measurements. It has been suggested elsewhere toattach an ultrasonic transceiver to a vascular catheter, either at ornear its tip. Patents issued to Liston, et al. (U.S. Pat. No.3,443,433), Millar (U.S. Pat. Nos. 4,175,566, 4,665,925, 4,771,782 and4,771,788), McLeod, et al. (U.S. Pat. No. 4,237,729), and Johnston (U.S.Pat. Nos. 4,637,401 and 4,674,336) reveal the use of ultrasonictransceivers in conjunction with arterial or venous catheters. In all ofthese references, however, the ultrasonic element is introduced tomeasure blood flow velocity only.

Moreover, these references teach only conventional methods ofpositioning a catheter. The placement of a catheter into or near theleft heart has, until now, been accomplished by fluoroscopicallymonitoring the catheter's progress through the circulatory system. Thereference of Johnston (U.S. Pat. No. 4,637,401) proposes inserting thecatheter in a vein and allowing it to be pulled downstream to the siteof interest; this technique is unsuitable, however, for reaching theleft heart chambers and the blood vessels immediately downstream.

Catheterization of the left heart requires upstream or retrogradeinsertion of a catheter and has typically involved the use offluoroscopic equipment, which is unavoidably bulky and expensive andtherefore restricts the available locations in which catheterizationscan be performed. A further drawback of fluoroscopy-guidedcatheterization arises when the catheter is insufficiently radiopaque,requiring the use of radiopaque indicators or plugs inserted at thecatheter tip, as suggested in U.S. Pat. No. 4,577,637. Yet anothershortcoming is the undesirable exposure of the patient to radiation overlong time periods, which necessarily occurs during fluoroscopy and whichmay pose a health risk as in the case of a pregnant patient. Stillanother drawback is the inability of conventional catheterizationsystems to accurately locate the specified position of the catheter tipin the heart or other area of the circulatory system, or to provide animage of the immediate area surrounding the catheter tip.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to overcome these and otherdifficulties associated with fluoroscopy-guided left heartcatheterization. This object is attained by the method of the presentinvention, in which a catheter having a Doppler ultrasound transceiverat its tip, or in the alternative, a guide wire provided with anultrasound transceiver at its tip, is advanced while a continuous signalgenerated by the transceiver is monitored by the physician ortechnician. By observing signal characteristics which are indicative ofblood flow direction, the operator is able to steer the catheter in theretrograde direction at each arterial branch, thereby eventuallyreaching the heart.

The inventive catheterization method has the advantage that nofluoroscopy or radiography is required to correctly position thecatheter tip in or near the left heart. Instead of using a cumbersomefluoroscopic apparatus, the physician or cardiac catheterizationtechnician can perform the procedure using a readily portable controldevice having an oscilloscope-type monitoring screen.

Another advantage of the inventive method is that catheters need not bemodified or equipped with radiopaque elements to enhance theirfluoroscopic visibility. Furthermore, the patient is not exposed toradiation during the procedure, allowing catheterizations to beperformed on individuals for whom a fluoroscopically-guidedcatheterization is contraindicated.

In addition, an ultrasonic imaging transducer, disposed at or near acatheter tip, may be used to provide a two-dimensional visual image ofthe area surrounding the tip or distally therefrom so as to facilitatethe placement of the catheter in various portions of the circulatorysystem. Furthermore, the imaging transducer may be advanced intospecified areas within the heart, such as into the coronary artery. Ifdesired, the present catheter or guide wire may be inserted into aflexible sheath or catheter having a transponder ring at its tip tofacilitate the determination of the location of the catheter within thebody by an esophageal or extracorporeal ultrasonic transducer.

These and other benefits of the present invention will be understoodmore clearly in connection with the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to several drawings, in which;

FIG. 1 is a perspective view of a multiple-lumen catheter suitable foruse in the present method;

FIG. 2 is a cross-sectional view of the catheter of FIG. 1, taken alongline 2--2 of FIG. 1 and in the direction generally indicated;

FIG. 3 is a longitudinal section of the catheter of FIG. 1, taken alongline 3--3 of FIG. 2 and in the direction generally indicated;

FIG. 4 is an end view of an alternative catheter configuration;

FIGS. 5A-C are representative displays on a monitor used in the methodof the present invention, showing tracings indicative of variouspositionings of the catheter tip;

FIG. 6 is a representative multi-functional display on a monitor used inthe method of the present invention;

FIG. 7 is a representative monitor display used in the method of thepresent invention, showing tracings indicative of various positioningsof the catheter tip as it advances through the femoral artery of a dog;

FIG. 8 is an end view of an alternate embodiment of a catheter suitablefor use with the present method;

FIG. 9 is an end view of a catheter suitable for use with the presentmethod and having a two-dimensional scanning type ultrasonic imagingtransducer inserted therein;

FIG. 10 is a fragmentary top perspective view of the two-dimensionalscanning imaging transducer shown in FIG. 9;

FIG. 11 is a diagrammatic sectional view of a portion of the human heartin which the present method may be practiced with the catheter of FIG.9;

FIG. 12 is a diagrammatic view of the monitor display generated by thecatheter of FIG. 9 employing the transducer of FIG. 10;

FIG. 13 is a diagrammatic view of the monitor display generated by anexternal ultrasonic transducer used with the catheter of FIG. 9;

FIG. 14 is a diagrammatic front elevational view of an alternateembodiment of a catheter suitable for use in the method of theinvention;

FIG. 15 is a longitudinal sectional view taken along the line 15-15 ofFIG. 14 and in the direction indicated generally; and

FIG. 16 is a diagrammatic front elevational view of an alternateembodiment of the catheter depicted in FIG. 14.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The inventive method is herein described primarily in connection withcatheterization of the left heart; however, it should be apparent thatother procedures are likewise possible using Doppler-guidedcatheterization.

A steerable catheter 10 is shown in FIGS. 1-3. Catheter 10 is amultiple-lumen catheter of well-known type, and has a first lumen 12which is capped at its tip or distal end 13 with a Doppler-typeultrasound transceiving crystal 18. Electrical leads 20 extend from thetransceiver 18, through the length of lumen 12, to a conventionalexternal power supply and control apparatus 25. If desired, theelectrical leads 20 from crystal 18 can extend through two separatedlumens, thereby eliminating the possiblity of an electrical shortcircuit.

A second lumen 14 is hollow and at its proximal end 15 is provided witha connector 17 which allows the attachment of a variety of instruments,such as a manometric device for obtaining measurements of blood pressureat the catheter tip 13 or a syringe for the injection of contrast mediaor therapeutic compounds. Lumen 14 may include two or more side holes 8(best seen in FIG. 1) near the tip 13 for echo contrast injection. Athird lumen 16 accommodates a guide wire 19 which may be of a J-tippedor other suitable type, with which the operator can steer the catheter10 during insertion.

Other catheter configurations may also be suitable for use with themethod of the present invention. The above-described catheter 10 has adiameter of approximately 7-8 French (F), or approximately 2.5 mm.Narrower catheter diameters of 5-7 F are attainable by using a two-lumencatheter, in which a a guide wire is fitted into the same lumen used forpressure measurement. A readily available Y-connector is then used atthe proximal catheter port to allow both guide wire manipulation andpressure readings.

Even narrower catheters may be used which have only one lumen. One suchcatheter 22 is shown in FIG. 4, and has a ring-shaped Dopplertransceiver 24 surrounding a single lumen 26 which is used for bothpressure measurement and a guide wire. In the case of catheter 22, theelectrical leads attached to transceiver 24 may be embedded in the wallof the catheter.

The Doppler ultrasound control apparatus or unit 25, which is connectedto the transceiver 18 by leads 20, serves as a power supply for thetransceiver which generates an ultrasound signal of approximately 20megahertz. The apparatus 25 also processes signals produced by thetransceiver 18, and displays those signals as a tracing on anoscilloscope-type monitor 27 (best seen in FIG. 5), to which the controlapparatus is electrically connected.

The catheter 10 is demarcated in centimeters 29 to identify the distancefrom the arterial insertion site. The guide wire 19 is also similarlydemarcated in centimeters to identify the distance that the end of thewire extends out of the catheter tip 13.

In the case of a cardiac catheterization, the catheter 10 is insertedinto the brachial or, preferably, the femoral artery using a suitableinsertion sheath (not shown). The catheter 10 is directed in theretrograde direction, i.e., against the flow of blood. This orientationof the catheter tip 13 is indicated by a shift in the display on themonitor 27 from the tracing 30 of FIG. 5a, which coincides with zeroblood flow, to the tracing 32 of FIG. 5b. The appearance ofupwardly-directed peaks 36 on the display is representative of bloodflow towards the Doppler transceiver during systole (i.e., contractionof the left ventricle). This is in contrast to the monitor display ofFIG. 5c, in which blood flows away from the transceiver and producessystolic peaks 38 of tracing 34 which are directed downwardly.

The catheter 10 is next advanced through the arterial tree towards theheart while the monitor display 27 is watched for any change in thetracing configuration. Should the operator accidentally guide thecatheter 10 into an incorrect arterial branch, the monitor tracing 30,32, 34 will show a downward deflection during systole instead of anupward one, indicating that the direction of catheter advancement is nolonger retrograde. The catheter 10 is then withdrawn slightly, androtated with possible guide wire adjustment. In this manner, thecatheter 10 is maneuvered into the correct vessel. Alternatively, thecatheter 10 may be advanced without the use of the guide wire 19. Thecatheter 10 may have sufficient rigidity and be of appropriate shape forsome patients to permit advancement by manual force and slight periodicrotation.

The catheter 10 is advanced until the aortic arch or a position superiorto the aortic valve is reached. Guidance and positioning of the catheterare facilitated by monitoring the blood pressure at the catheter tip 13,using a manometric transducer 39 connected to the open lumen 14.Advantageously, the output of the transducer 39 as well as the patient'selectrocardiograph (EKG) and the Doppler transceiver signal may besimultaneously displayed on a single monitor as shown in FIG. 6, inwhich tracings 40, 42, and 44 correspond to the EKG, pressure andDoppler ultrasound signals, respectively.

The final positioning of the catheter tip 13 can be accomplished by anyof a number of non-fluoroscopic techniques. Guide wire manipulation mayhelp crossing the aortic valve so as to enter the left ventricularchamber. The operator may be able to rely on pressure readings toestablish that the left heart ventricle has been reached. If desired, anexternal or esophageal ultrasound transducer may be used in conjunctionwith a transponder to accurately locate the catheter tip 13. This secondultrasound transducer may also be used to observe the location of themetallic catheter tip within the heart.

Once the catheter 10 has been properly placed, a variety of proceduresmay be carried out using the open catheter lumen 14 (as, for example,the measurement of left ventricular pressures or the injection ofechogenic contrast materials for myocardial ultrasound perfusionanalysis and valvular regurgitation analysis). In other cases, such aswhere a different type of catheter is needed, the Doppler-guidedcatheter 10 may be withdrawn while leaving the guide wire 19 in place.The desired catheter is then inserted over the guide wire 19, and theguide wire withdrawn if necessary. In this fashion, the present methodcan be used to place any type of catheter in or near the heart.

The advantages of the present method are further apparent in the case ofa patient having a stenotic aortic valve. Cardiac catheterization isfrequently difficult because of the partially occluded condition of sucha valve. Using the present Doppler-guided catheter 10, however, theoperator is readily able to identify the exact location and timing ofpeak flow through even a badly stenosed valve, and to insert thecatheter tip 13 into the left heart. Likewise, the present method workswell even in cases of arterial narrowing as by atherosclerosis, as theincreased blood velocity through the affected vessel enhances the upwarddeflection of the ultrasound tracing. The catheter could also be usedfor guidance placement for an intra-aortic balloon pumping device.

The doppler wave form in the aorta could also be used to calculatestroke volume and therefore cardiac output (requires knowledge of aorticroot diameter, which can be obtained with standard echocardiographictechniques).

Although the description of the above method pertains to cardiaccatheterization, it should be noted that Doppler-guided retrogradecatherterization can be used equally well in studies of blood vessels ororgans intermediate to the point of catheter insertion and the heart.For example, ultrasonic angiography of the iliac or renal arteries canbe conducted by advancing the catheter tip just beyond the junction ofthe abdominal aorta and the artery in question. Using an externalultrasound transducer in combination with a transponder, the catheter ispositioned precisely and used to inject echogenic contrast material.Similarly, blood flow in the carotid arteries can be studied by choosingan appropriate injection point in the aortic arch. A further possibleuse of this method is in venous anterograde catheterization, in which aDoppler-guided catheter is inserted in a suitable vein and advanceddownstream towards the vena cava and right heart.

EXAMPLE I

The above method was used in performing the Doppler-guided left heartcatheterization of dogs.

A Doppler flow catheter was inserted through the femoral artery of thedog. The monitor display showed that the tracing 46 on the left side ofthe graph (see FIG. 7) consisted of downwardly directed peaks below thebase line which indicated that the blood flow was going toward thetransducer, signifying that the guide catheter was being advanced in thecorrect direction. The right side of the graph of FIG. 7 showed upwardlydirected peaks 48 above the base line which indicated that the guidecatheter had been inadvertently advanced into the wrong vessel.

FIG. 7 shows a tracing 46, 48 having downwardly directed peaks whichindicates that the blood flow was going toward the transducer ascompared to FIGS. 5 and 6 which show the inverse. This differencebetween FIGS. 5, 6, and FIG. 7 was due to a change in the polarity ofequipment used in the respective tests. Responsive to an abnormaltracing on the monitor display, as indicted in the above example, thecatheter was slightly withdrawn from the artery, rotated and advanced inthe direction where there was positive flow towards the transducer.

Following catheterization of the test animals, fluoroscopy was used toconfirm that the catheter tip had been successfully positioned.

Referring now to FIG. 8, an alternate embodiment of the catheter of theinvention is indicated generally at 50. The catheter 50 is generally ofthe same design as is the catheter 10, and as such identical componentswill be assigned identical reference numerals, with the addition of thesubscript "a". Hence, the lumen 14 becomes 14a, etc. Thus, the catheter50 includes a Doppler transceiver 18a to which are connected a pair oflead wires 20a, each of which is inserted through a corresponding upperlumen 51, 52. The lead wires 20a are placed in a separate lumens toprevent short circuits. In the preferred embodiment, the lumens 51, 52are relatively smaller in diameter than the larger lower lumen 14a. Itis also preferred that the transceiver 18a is configured to nest withina hemispherical recess 53 in the catheter tip 13a. The transceiver 18ais thus prevented from becoming detached from, or misaligned upon, thecatheter tip 13a. The lumen 14a may be equipped with a guide wire 19aand/or a pressure transducer (not shown).

The catheter 50 having the Doppler transceiver 18a may be used with acatheter sheath, and may be withdrawn from the sheath and replaced by acatheter 50' having an ultrasonic imaging transducer 54 inserted therein(best seen in FIGS. 10 and 11). The transducer 54 is preferably of thehigh frequency (approximately 30-50 Mhz), two-dimensional scanning type.The scanning may be accomplished by a rotating reflector 56 as is knownin the art, by a conventional phased array scanner, as well as by othersimilarly effective scanning devices. The transducer 54 is disposed atthe end of catheter 50' to provide a two-dimensional image of theportion of the heart or other region of the circulatory system whichdirectly surrounds the tip of catheter 50'. In addition, the transducer54 is preferably electrically connected to a monitor 58 (best seen inFIG. 12) so as to create a two-dimensional image display 60.

Referring now to FIG. 9, it has been found that in order to obtain themaximum benefit of the above-described retrograde catheterization andimaging technique, it is advisable for the operator to be fairly certainof the exact location of the catheter tip within the circulatory system.To this end, the catheters 50 and 50' may be fabricated to be ofsufficiently small dimension to be slidably inserted into a flexiblecatheter guiding sheath 62 as is known in the art. The sheath 62 may beequipped with a transponder 64, which may be configured as a ringannularly disposed around the periphery of the sheath 62. If desired,the transponder 64 may be located near the tip of the catheter 50'.

Referring now to FIGS. 9 and 13, the transponder 64 senses a pulsatingultrasonic signal which is emitted by an ultrasonic transducer 68located outside the body. Signals generated by both the transponder 64and the transducer 68 are integrated so as to generate on a monitor 70 atwo-dimensional display image 72 of a region of the heart in which thetip of the sheath 62 is located. The action of the impulses sensed bythe transponder 64 creates a flashing or similar marker display 74 onthe display 72 of the monitor 70. In this manner, the precise positionof the catheter tip 13a and the tip of the sheath 62 may be discerned.By visually monitoring the displays 60 and 72, the operator mayaccurately guide the sheath 62 into specified areas of the heart, suchas the coronary ostium, so that ultrasonic contrast media may beadministered, and/or that the catheter 50' can be advanced into thecoronary artery to image the arterial walls.

Referring now to FIG. 11, a partial cross-sectional view of the heart isdepicted in which the heart is generally designated 76. Blood is pumpedfrom the heart 76 via the ascending aorta 78, which is also the vesselinto which the sheath 62, containing the catheter 50, is guided in theretrograde direction through the use of the Doppler transceiver 18a andas described above in relation to FIGS. 1-6, 8, 9 and 13. Ultimately,the tip 80 of the sheath 62 is positioned at the entrance 82 of thecoronary artery 84.

At this time, the catheter 50 bearing the Doppler transceiver 18a iswithdrawn from the sheath 62 and is replaced by the catheter 50' bearingthe ultrasonic imaging transducer 54 (best seen in FIGS. 9 and 10). Thecatheter 50' is then inserted into the sheath 62 until it reaches thetip 80. The transducer 54 is manipulated into the coronary artery 84through the use of a guide wire 86 mounted at the tip of the transducer54. As it progresses, and through the rotation of the reflector 56, thetransducer 54 provides the continuous image 60 of the condition of theinterior of the arterial wall. It is also contemplated that thetransceiver 18a and the transducer 54 may be combined into a singlecatheter.

Referring now to FIG. 12, if desired, the image display 60 may becombined with the displays 40, 42, 44 and 72 (best seen in FIGS. 6 and13), either on an adjacent monitor 58, or on the same monitor 27. If thetransponder 64 is provided, the various monitored parameters may thus beincorporated into a single instrument console to enable continuous andaccurate monitoring of the position of the catheter tip 13a in thecirculatory system. Naturally, due to the limited number of lumens suchas 51, 52 and 14a in the catheter 50 (and lumens 12 and 14 in thecatheter 10) as presently described, it may not be possible to monitorall of the functions simultaneously.

Thus, through the use of the catheter 50, the Doppler transceiver 18a isused as a locating mechanism to advance in the retrograde direction andposition the catheter at a specified portion of the heart, such as atthe entry way of the coronary artery. Once the tip 13a of the catheter50 is properly located by means of the above-described Doppler-guidedretrograde catheterization (with the possible assistance of associatedtransponder technology), the ultrasonic transducer 54 may be used toobserve the condition of arterial walls, including the walls of thecoronary artery. A significant advantage of the present system is thatthe heart may be catheterized without the use of X-rays or otherfluoroscopic techniques.

Referring now to FIGS. 14 and 15, an alternate embodiment of thecatheter depicted in FIGS. 1-3 is generally designated 90. The catheter90 is a single-lumen catheter as is well-known in the art, and has abody 92 with a single lumen 94. It is also contemplated that the presentembodiment may alternatively be employed in catheters having multiplelumens (best seen in FIGS. 1-3, 8 and 16)

A guide wire 96, similar in structure and function to the guide wire 19,is disposed in the lumen 94. The guide wire 96 differs principally fromthe wire 19 in that a Doppler-type ultrasound transceiving crystal ortransceiver 98 is mounted to the tip 100 of the guide wire 96.Electrical leads 102 extend from the transceiver 98, through the lengthof the lumen 94, to the conventional external power supply and controlapparatus 25. If desired, the guide wire 96 may be provided in coaxialform, and the leads 102 may be passed centrally therethrough, as shownin FIG. 15.

In operation, the catheter 90 is utilized in a similar manner as thecatheters 10 and 50, described in relation to FIGS. 1-8. Thus, in thecase of a cardiac catheterization, the catheter 90 is inserted into thebrachial or, preferably, the femoral artery using a suitable insertionsheath (not shown). The Doppler transceiver 98 is advanced to theforward tip of the catheter body 92, or beyond, by manipulation of guidewire 96. Blood flowing past the transceiver will create a signal whichis ultimately displayed on monitor 27. The catheter 90 is advanced inthe retrograde direction, and the movement of the catheter through thevessel is monitored through observation of the display on the monitor 27as described previously.

A significant advantage of the catheter 90 is that it may be made ofsmaller diameter than the catheter 10, for use in smaller vessels, or inpediatric applications. Regardless of its size, once the catheter 90 hasreached the desired destination within the circulatory system, the guidewire 96 may be withdrawn and replaced with other monitoring equipment,such as a pressure monitor, an ultrasonic imaging transducer similar tothe transducer 54 (best seen in FIG. 10), contrast injection or atransponder 64', which is similar in structure and function to thetransponder 64. The transponder 64' may be disposed about the catheter90 and employed with an esophageal or extracorporeal ultrasonictransducer 68 for locating the tip of the catheter 90 as described inrelation to FIGS. 9 and 11.

Referring now to FIG. 16, an alternate embodiment of the catheter 90 isgenerally designated 90', and contains similar components, which aredesignated with identical reference numerals each having a (') primedesignation. The principal difference between the catheters 90 and 90'is that the catheter body 92' in catheter 90' is of the multiple lumentype, having an additional lumen 104, while the catheter body 92 in thecatheter 90 is of the single lumen type. The provision of additionallumens has certain advantages regarding the simultaneous use ofdiagnostic equipment as is described above and is known in the art. Inall other respects, the structure and function of catheters 90 and 90'is identical, including the option of use with transponder technology.

The above description of the inventive method and apparatus are for thepurpose of better illustrating its use, and are not intended to limitthe scope of the invention. It will be appreciated by those familiarwith the art that variations in the materials and techniques describedherein are within the ambit of the claims which follow.

I claim:
 1. A method for the intravascular catheterization of a highermammal without fluoroscopy, comprising:inserting into a peripheral bloodvessel a catheter having an ultrasound transceiver mounted to a guidewire, said catheter being inserted into the vessel and directed in theretrograde direction; generating from signals produced by the ultrasoundtransceiver a continuous indication of the direction of blood flowrelative to the catheter; displaying said indication of blood flowdirection; and advancing the catheter towards the heart in theretrograde direction in accordance with the indication of blood flowdirection; whereby the catheter is selectively positioned at a desiredlocation within the circulatory system of the mammal.
 2. The method ofclaim 1 wherein the peripheral blood vessel is an artery.
 3. The methodof claim 2 wherein the artery is selected from the group consisting ofthe brachial and femoral arteries.
 4. The method of claim 2 wherein thecatheter is provided with means for obtaining indications of bloodpressure within the artery.
 5. The method of claim 4 wherein the meansfor obtaining pressure indications comprise a pressure transducerconnected to the proximal end of a lumen extending through the catheter.6. The method of claim 4 wherein the catheter is advanced in accordancewith indications of both pressure and blood flow direction.
 7. Themethod of claim 1 wherein the guide wire has a tip and the ultrasoundtransceiver is located at the tip of the guide wire.
 8. The method ofclaim 1 further including providing said catheter with a transponderadjacent its tip for sensing ultrasonic impulses.
 9. A method for thecatheterization of a human patient without fluoroscopy,comprising:inserting a catheter into a peripheral artery selected fromthe group consisting of the brachial and femoral arteries, the catheterhaving a Doppler ultrasound transceiver operationally disposed relativeto its tip, at least one lumen extending the length of the catheter,said catheter being inserted into the vessel in the retrogradedirection; generating from signals produced by the ultrasoundtransceiver a continuous indication of the direction of blood flowrelative to the catheter tip; selectively connecting a pressuretransducer to the catheter lumen and generating from signals produced bythe pressure transducer an indication of blood pressure at the cathetertip; visually displaying the indications of pressure and blood flowdirection; and advancing the catheter towards the heart in theretrograde direction in accordance with the indications of pressure andblood flow direction while steering the catheter; whereby the cathetertip is selectively positioned at a desired location within thecirculatory system of the patient.
 10. The method of claim 9 wherein thecatheter is provided with a guide wire and the transceiver is disposedon the guide wire.
 11. The method of claim 10 wherein the transceiver islocated at the tip of the guide wire.
 12. The method of claim 11 furtherincluding providing said catheter with a transponder adjacent its tipfor sensing ultrasonic impulses, and providing an ultrasonic transducerfor monitoring impulses sensed by said transponder.
 13. A device for theintravascular catheterization of a higher mammal without fluoroscopy,comprising:a catheter capable of insertion into a peripheral bloodvessel, the catheter having at least one lumen, and a guide wireslidably disposed in the lumen for manipulation independent of thecatheter; an ultrasound transceiver secured to the tip of the guidewire, the transceiver being capable of producing an electrical signalindicative of the direction of blood flow relative to the catheter; acontrol unit capable of supplying power to the transceiver and ofgenerating from the signal produced by the transceiver a continuousindication of blood flow direction; wires connected to the transceiver,extending through the guide wire from its tip towards its proximal endand connected to the control unit; and a display monitor visible to anoperator of the device, the monitor being electrically connected to thecontrol unit and capable of visually displaying the indication of bloodflow direction; whereby the operator is able, in accordance with theindication of blood flow direction, to advance and direct the catheterin the retrograde direction towards and selectively position thecatheter in a desired location within the circulatory system of themammal.
 14. The device of claim 13 additionally comprising a pluralityof lumens in the catheter, a pressure transducer in communication withone of the lumens of the catheter and capable of producing an electricalsignal indicative of blood pressure at the catheter tip, the transducerbeing electrically connected to the control unit, the control unit beingadditionally capable of generating from the signal produced by thetransducer an indication of blood pressure, and the display monitorbeing additionally capable of visually displaying the indication ofblood pressure,whereby the operator is able to advance and position thecatheter in accordance with the indications of both pressure and bloodflow direction.
 15. The device of claim 13 wherein said catheter isprovided with a transponder, and including a second ultrasonictransducer located outside the body for receiving impulses sensed bysaid transponder.